The BLS publishes pretty comprehensive statistics for the US:

http://www.bls.gov/news.release/empsit.toc.htm

They still have some of the caveats that you mention, but not as many (and many of the reports are for some purpose where the caveat is sensible).

For instance, this table breaks down full and part time employment:

http://www.bls.gov/news.release/empsit.t08.htm